United States Department of Agriculture 

Animal and Plant Health Inspection Service 

WS Directive 2.320 02/06/04

INVASIVE SPECIES DAMAGE MANAGEMENT

1. PURPOSE 

To provide guidelines for WS actions in the control of invasive 

species, including feral animals and exotic wildlife in 

fulfillment of the objectives of Executive Order 13112 (1999), 

the Nonindigenous Aquatic Nuisance Prevention and Control Act of 

1990 as amended (1996), the Endangered Species Act of 1973 as 

amended when invasive vertebrate species threaten those species 

covered under the Act, and the Animal Damage Control Act of 1931 

as amended. 

2. REPLACEMENT HIGHLIGHTS 

This directive replaces ADC Directives 2.320 and 2.325 dated 

3/26/93. 

3. DEFINITIONS 

Definitions for this Directive are taken from Executive Order 

13112 on Invasive Species as follows: 

a. "Alien species" means, with respect to a particular ecosystem, 

any species, including its seeds, eggs, spores, or other 

biological material capable of propagating that species, that is 

not native to that ecosystem. 

b. "Control" means, as appropriate, eradicating, suppressing, 

reducing, or managing invasive species populations, preventing 

spread of invasive species from areas where they are present, and 

taking steps such as restoration of native species and habitats 

to reduce the effects of invasive species and to prevent further 

invasions. 

c. "Introduction" means the intentional or unintentional escape, 

release, dissemination, or placement of a species into an 

ecosystem as a result of human activity. 

d. "Invasive species" means an alien species whose introduction 

does or is likely to cause economic or environmental harm or harm 

to human health. 

4. BACKGROUND 

Invasive species, including feral and exotic animals, may 

threaten or damage human health or safety, agriculture, natural 

resources, or property, and may be vectors of diseases for 
humans, domestic animals, or wildlife. Executive Order (EO) 

13112 (Clinton, 1999) states that each Federal agency whose 

actions may affect the status of invasive species shall, to the 

extent practicable and permitted by law, take steps to control 

damage caused by such species. Steps outlined in the Order 

included preventing the introductions of invasive species and 

detection and rapid response to, and control of, populations of 

such species in a cost-effective and environmentally sound 

manner, and conducting research on, and development of 

technologies to prevent introduction and to provide for 

environmentally sound control of, invasive species. WS is 

further authorized by 50CFR30(1998) to conduct activities in the 

control of feral animals, including horses, burros, cattle, 

swine, sheep, goats, reindeer, dogs, and cats, without ownership, 

that have reverted to the wild from a domestic state. The Wild 

Free-roaming Horses and Burros Act (16 U.S.C. Subsections 1331-

1340) of 1976 places management of both horses and burros under 

the jurisdiction of the Secretaries of Agriculture-through the 

Forest Service, and The Secretary of the Interior through the 

Bureau of Land Management, Further, wild horses and burros may be 

protected under this Act and Wildlife Services actions related to 

these animals are always conducted pursuant to the management 

objectives of the Forest Service or the Bureau of Land 

Management, as appropriate. The Nonindigenous Aquatic Nuisance 

Prevention and Control Act of 1990, reauthorized and amended as 

the National Invasive Species Act of 1996 further authorizes 

Federal agencies to prevent and control infestations of the 

coastal and inland waters of the United States by the zebra 

mussel and other nonindigenous aquatic nuisance species. 

The National Invasive Species Council (NISC) was formed pursuant 

to EO 13122 to provide national leadership and oversight on 

invasive species and to see that Federal agency activities are 

coordinated, effective, work in partnership with States, and 

provide for public input and participation. The NISC (2001) 

developed a Management Plan which outlined participant roles, 

action plans, and authorities. Ongoing initiatives of the NISC 

have been implemented as part of a national invasive species 

management program. WS collaborates with the NISC in developing 

strategies for addressing invasive species damage. 

5. POLICY 

WS personnel will provide technical assistance to Federal, State, 

Tribal, United States Territorial and Local governments, private 

industry, and/or individuals for managing damage caused by 

vertebrate invasive species, including feral and exotic animals, 

or to suppress disease. Direct control may be provided at the 

discretion of the State Director, as appropriate. All direct 

control should be coordinated with the appropriate animal or 

wildlife management authorities, and law enforcement agencies. 

The National Wildlife Research Center shall, contingent upon 

available funding and staffing, cooperate and collaborate with 

Federal, State, Tribal, and Local agencies, other public and 
private entities involved in the control of invasive species, and 

State WS program managers in conducting research designed to 

achieve the objectives of Executive Order 13112 and other Acts 

and authorities referenced in this Directive. 

6. REFERENCES 

Animal Damage Control Act. 1931, as amended. 7 United States Code 

(426-426c). 

Clinton, W.J. 1999. Executive Order 13112. Invasive species. The 

White House, Office of the Press Secretary. 

Endangered Species Act. 1973, as amended. Code of Federal 

Regulation, Title 50, Part 17. 

NISC (National Invasive Species Council). 2001. Management plan; 

meeting the invasive species challenge. 74pp. 

Nonindigenous Aquatic Nuisance Prevention and Control Act. 1990, 

as amended. The National Invasive Species Act of 1996. 

50 CFR 30. 1998. Code of Federal Regulation, Title 50--Wildlife 

and Fisheries Chapter I—United States Fish and Wildlife 

Service, Department of the Interior Part 30—Range and Feral 

Animal Management. 

Deputy Administrator